In biological purification of waste waters which contain organic solids, sediments are formed which are so firm that anaerobic zones occur within them. This leads to the creation of offensive odors and sedimentation. Dissolved oxygen is required to prevent the formation of these offensive odors and to biologically break down the organic matter within the water. Moreover, a certain amount of dissolved oxygen is required to sustain various aquatic organisms. Increasing the dissolved oxygen content of other substances, such as sludge, is necessary also. The supply oxygen to water, and the circulation of oxygen and water is also important to aquaculture, wherein fish, shellfish, and other marine life are kept in bounded natural bodies of water, tanks, or aquariums for commercial breeding purposes.
Aeration apparatus are used to increase the dissolved oxygen content of the treated substance and thereby purify it, and to supply and circulate oxygen to support marine life. One type of aeration apparatus is a propeller type aerator. These devices use an electric motor driven rotating propeller disposed below the surface of the substance being treated. The propeller draws in atmospheric air from an intake port through a draft tube and discharges it into the substance e.g. the waste water being treated or the water containing marine life.
Propeller type aerators can range in size, for example, from 1/2 hp to 100 hp. As the size of the aerator increases, the size of its support system likewise increases. The type of support system also depends on the type and size of the aerated substance container (e.g., basin, lagoon, or tank).
Known aeration systems rigidly support the aerator on a support system. In such a rigid support system the propeller discharges air along a relatively narrow section of the water in one direction only. In order to adequately aerate an entire large pond of water a system comprised of a plurality aerators is required. In locations where only a single aerator can be installed, for example where a single aerator is stationarily mounted on a wall of a pool, only a narrow frustoconical section of the pool is directly aerated. The remainder of the pool is not aerated until the directly aerated section diffuses.